It is increasingly evident that 1) the rate of energy utilization is coupled to CNS function and 2) that the cyclic nucleotides as neuroeffectors may play an important role in neuronal excitability. Using the levels of both energy metabolites and cyclic nucleotides as an indicator of brain activity, the effect of several neurotropic agents including 1) convulsants, 2) anticonvulsants and 3) anesthetics were examined in the cerebral cortex and cerebellum. Generally, these drugs have little or no effect on the concentrations of the energy metabolites. However, with the onset of seizures following treatment with convulsants, there was a decline in the energy status of the tissues. While the levels of cyclic AMP increased during the tonic extensor phase of convulsions, it was not generally responsive to pharmacological manipulation. In contrast, cyclic GMP levels in the cerebellum were depressed by convulsants and anesthetics and elevated by convulsants. Although cyclic GMP in the cerebral cortex was similarly affected, the changes were not as dramatic.